Described herein are aspects generally related to communication systems, and more particularly, to configuring reference signals is wireless communications.
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of a telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, further improvements in LTE technology may be desired. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In LTE, some reference signals (RS), such as channel state information (CSI)-RS and user equipment (UE)-RS, may be scheduled for transmission in multiple symbols (e.g., orthogonal frequency division multiplexing (OFDM) symbols, single carrier frequency division multiplexing (SC-FDM) symbols, etc.) of a subframe, where the subframe is a 1 millisecond (ms) transmission time interval (TTI). Scheduling of the RSs may be based on a number of antenna ports corresponding to the RS transmission. In considering shorter duration TTIs for low latency communications (e.g., a symbol, two-symbol, slot, etc. TTI), using the same scheduling for CSI-RS, UE-RS, or other RSs per TTI may utilize more bandwidth than desired, which may lessen the performance advantages of selecting the shorter duration TTI.